tdb: add TDB_MUTEX_LOCKING support

This adds optional support for locking based on
shared robust mutexes.

The caller can use the TDB_MUTEX_LOCKING flag
together with TDB_CLEAR_IF_FIRST after verifying
with tdb_runtime_check_for_robust_mutexes() that
it's supported by the current system.

The caller should be aware that using TDB_MUTEX_LOCKING
implies some limitations, e.g. it's not possible to
have multiple read chainlocks on a given hash chain
from multiple processes.

Note: that this doesn't make tdb thread safe!

Pair-Programmed-With: Stefan Metzmacher <metze@samba.org>
Pair-Programmed-With: Michael Adam <obnox@samba.org>
Signed-off-by: Volker Lendecke <vl@samba.org>
Signed-off-by: Stefan Metzmacher <metze@samba.org>
Signed-off-by: Michael Adam <obnox@samba.org>
Reviewed-by: Jeremy Allison <jra@samba.org>

1 files changed, 29 insertions, 7 deletions

diff --git a/lib/tdb/wscript b/lib/tdb/wscript
index 70196938ed2..6243ccff8df 100644
--- a/lib/tdb/wscript
+++ b/lib/tdb/wscript
@@ -1,7 +1,7 @@
 #!/usr/bin/env python
 
 APPNAME = 'tdb'
-VERSION = '1.2.13'
+VERSION = '1.3.0'
 
 blddir = 'bin'
 
@@ -46,6 +46,10 @@ def set_options(opt):
     opt.BUILTIN_DEFAULT('replace')
     opt.PRIVATE_EXTENSION_DEFAULT('tdb', noextension='tdb')
     opt.RECURSE('lib/replace')
+    opt.add_option('--disable-tdb-mutex-locking',
+                   help=("Disable the use of pthread robust mutexes"),
+                   action="store_true", dest='disable_tdb_mutex_locking',
+                   default=False)
     if opt.IN_LAUNCH_DIR():
         opt.add_option('--disable-python',
                        help=("disable the pytdb module"),
@@ -53,6 +57,11 @@ def set_options(opt):
 
 
 def configure(conf):
+    conf.env.disable_tdb_mutex_locking = getattr(Options.options,
+                                                 'disable_tdb_mutex_locking',
+                                                 False)
+    if not conf.env.disable_tdb_mutex_locking:
+        conf.env.replace_add_global_pthread = True
     conf.RECURSE('lib/replace')
 
     conf.env.standalone_tdb = conf.IN_LAUNCH_DIR()
@@ -68,6 +77,11 @@ def configure(conf):
 
     conf.env.disable_python = getattr(Options.options, 'disable_python', False)
 
+    if (conf.CONFIG_SET('HAVE_ROBUST_MUTEXES') and
+        conf.env.building_tdb and
+        not conf.env.disable_tdb_mutex_locking):
+        conf.define('USE_TDB_MUTEX_LOCKING', 1)
+
     conf.CHECK_XSLTPROC_MANPAGES()
 
     if not conf.env.disable_python:
@@ -87,10 +101,12 @@ def configure(conf):
 def build(bld):
     bld.RECURSE('lib/replace')
 
-    COMMON_SRC = bld.SUBDIR('common',
-                            '''check.c error.c tdb.c traverse.c
-                            freelistcheck.c lock.c dump.c freelist.c
-                            io.c open.c transaction.c hash.c summary.c rescue.c''')
+    COMMON_FILES='''check.c error.c tdb.c traverse.c
+                    freelistcheck.c lock.c dump.c freelist.c
+                    io.c open.c transaction.c hash.c summary.c rescue.c
+                    mutex.c'''
+
+    COMMON_SRC = bld.SUBDIR('common', COMMON_FILES)
 
     if bld.env.standalone_tdb:
         bld.env.PKGCONFIGDIR = '${LIBDIR}/pkgconfig'
@@ -99,9 +115,15 @@ def build(bld):
         private_library = True
 
     if not bld.CONFIG_SET('USING_SYSTEM_TDB'):
+
+        tdb_deps = 'replace'
+
+        if bld.CONFIG_SET('USE_TDB_MUTEX_LOCKING'):
+            tdb_deps += ' pthread'
+
         bld.SAMBA_LIBRARY('tdb',
                           COMMON_SRC,
-                          deps='replace',
+                          deps=tdb_deps,
                           includes='include',
                           abi_directory='ABI',
                           abi_match='tdb_*',
@@ -137,7 +159,7 @@ def build(bld):
         # FIXME: This hardcoded list is stupid, stupid, stupid.
         bld.SAMBA_SUBSYSTEM('tdb-test-helpers',
                             'test/external-agent.c test/lock-tracking.c test/logging.c',
-                            'replace',
+                            tdb_deps,
                             includes='include')
 
         for t in tdb1_unit_tests: